Labels are a cognitive double-edged sword. We need to categorize the world in order to mentally capture it – labels help us organize our mental maps of the overwhelming complexity of things and to communicate with each other. But labels can also be mental prisons, when they substitute for a thorough, nuanced, or individualized assessment – when categorization becomes pigeon-holing.

We use many labels in our writings here, out of necessity, and we try to be consistent and thoughtful in how we define the labels that we use, recognizing that any sufficiently complex category will be necessarily fuzzy around the edges. We have certainly used a great deal of electrons discussing what exactly is science-based medicine, and that the label of so-called alternative medicine is really a false category, used mainly for marketing and lobbying (hence the caveat of “so-called”).

We get accused of using some labels for propaganda purposes, particularly “antivaccinationist” (often shortened to “antivaxer”). Also “denier” or “denialist”, as in germ-theory denier. Even though we often apply labels to ourselves, no one likes having an unflattering label applied to them, and so we have frequent push-back against our use of the above terms.

As with many such terms, it is really defining one end of a continuum and we recognize that there is a broad range of attitudes and opinions regarding vaccines. Not all doubts about the safety of vaccines, nor skepticism toward the motives and ethics of corporations or the effectiveness of regulatory bodies, is necessarily “antivaccine”. We are, however, frequently accused of implying exactly that, especially by those who are ironically far to the anti-vaccine end of the spectrum.

A recent e-mail to me is very typical:

I have a few questions for you. Would you give a vaccine using a formula that was a hundred years old to your children? Or if you could go into the future a hundred years, would you use today’s vaccines? If you had three children, and two died soon after being vaccinated, would you give the third the same vaccine? I’m sure some of you would not, which means you are in the same boat as the anti-vaccers. I have a problem with the way you lump everyone who disagrees with you into one hated group. Though I believe in taking the natural approach to health, the reason I avoid vaccines is because of some it’s contents, mercury, for example. I don’t believe all vaccines are bad, and I don’t blindly accept that all vaccines are safe.

I will first define what I think are some useful subcategories to the anti-vaccine landscape. The first sub-category is not truly anti-vaccine, but can be made to feel as if they are being lumped in with extremists – and that is well-meaning parents who are simply misinformed or confused.

To be absolutely clear, we are not critical of this group. They are the victims of misinformation and propaganda. For example, the e-mailer above claims that they avoid vaccines because they contain mercury. However, mercury was removed from the routine childhood vaccine schedule in the US by 2002. Tiny doses of mercury (in thimerosal) is still present in some, but not all, flu vaccines. You can get all the vaccines you need without any mercury (except for insignificant trace amounts). I should also mention that the doses of mercury in vaccines prior to 2002 was tiny, that it is in the form of ethylmercury, which is much less toxic than methylmercury (the form that is more likely to be encountered in the environment), and that the evidence does not show any link between mercury in vaccines and any adverse outcome.

So why are we still talking about mercury in vaccines? Because those who are genuinely anti-vaccine keep using this canard as a scare tactic. I use the term antivaxer not to refer to the victims of propaganda but to those who spread misinformation and propaganda about vaccines because their agenda is to oppose vaccines.

As my colleague David Gorski has written many times – with an antivaxer it’s always about the vaccine. Not safety, not autism, not any one ingredient in vaccines – it’s about the vaccines themselves. This is the “true antivaxer” category – an anti-vaccine activist.

This subgroup (not really a subgroup, it is, rather, what we actually mean by antivaxer) can be divided into several subgroups by how they got to their anti-vaccine ideology. Some in the antivaxer camp are part of what has been called for years the “mercury militia.” They are convinced that mercury toxicity is responsible for a long list of human ills, and they jumped on the anti-vaccine bandwagon because of the mercury (thimerosal) issue.

Another antivaccine subgroup are the alternative medicine proponents and practitioners. They generally do not take a science-based approach to health care, and may endorse one or more specific unscientific, mystical, or spiritual approaches. They often oppose vaccines simply because vaccines are in the science-based camp, and conveniently they have their own alternatives to sell you.

The e-mailer above may be affected by this CAM subgroup also, given her endorsement of the naturalistic fallacy. The idea that “natural” (never well defined) is inherently more safe and effective than anything “artificial” (also not clearly defined) is perhaps the most common and most effective bit of CAM propaganda, and in fact goes back much farther than the modern CAM movement. Ironically it is a label that is used to “greenwash” over the real issues – evidence for safety and effectiveness and scientific plausibility.

A third category in the antivaxer camp are those who have a specific ideology that opposes the use of medical interventions in general, or specific interventions that include vaccines (such as Christian Scientists). In this case the anti-vaccine stance is a literal religious belief. They are often happy, however, to endorse the propaganda of the previous groups in order to bolster and justify the antivaccine position they take for primarily religious reasons.

The final category (at least on my list – acknowledging that no such list can be all-encompassing) are environmentalists. I am not saying that environmentalists are antivaccine, but rather that some individuals’ journey to the antivaccine camp passes through their somewhat extreme environmentalism. In this world view corporations are evil until proven otherwise, and environmental toxins are a massive cause of human disease and suffering. They see vaccines as one more environmental toxin (and here there is large overlap with the “mercury militia”), and readily accept that there are no limits to the malfeasance of large corporations in pursuit of profits. Robert Kennedy Jr. most famously fits into this category, in my opinion.

The e-mailer hints at the conspiracy attitude with the comment that they do not blindly accept that all vaccines are safe. This is a straw man argument, since neither do vaccine supporters. There is a copious amount of evidence for vaccine safety. It is perhaps the safest medical intervention we have devised – millions of doses given with few serious adverse outcomes. But we always want more data, and so we endorse monitoring vaccine safety and performing more studies as vaccines evolve and new vaccines are developed.

Like all such categories, they are not clean. There is a great deal of overlap and ideological contamination. These are peaks in a complex landscape, but not completely discrete groups. But the one thing they all have in common is that they oppose vaccines, they engage in the abuse of science in order to engage in an antivaccine agenda, and they spread misinformation and scaremongering about vaccines.

Many people, however, have questions and concerns about vaccines. This does not make one an antivaxer. It is reasonable and healthy to have questions about any health intervention, especially when a parent is making such decisions for their children. We encourage questioning. The antivaxers (ironically while crying for informed consent) have made making an informed decision more difficult by muddying the waters. It is difficult to counter a dedicated campaign of misinformation, as it is a lot easier to sow doubt and confusion than to correct every piece of bad information.

I also want to emphasize that I encourage a doubting and questioning attitude. It is good to be skeptical of all claims, but healthy skepticism can easily slide into cynicism or denial. It is important to question all sides and see who has the better and more authoritative answers to questions.

With regard to vaccines, the data is there, published in the peer-reviewed literature. Many professional groups have thoroughly analyzed the literature and independently concluded that vaccines are safe and effective. On the other side are those promoting bad science, bad logic, conspiracy theories, and unwarranted fears that always find their way back to vaccines. That is not a healthy approach to the evidence, no matter what you label it.